1. Technical Field
The present invention relates generally to canopy-type aircraft cargo doors; and, more particularly, to relatively large cargo doors sized to permit off-loading and on-loading of containerized baggage, containerized and/or palletized cargo, and similar relatively large items including, for example, a palletized aircraft spare engine. In its principal aspects, the invention relates to an electrically operated, outwardly opening, large canopy-type aircraft cargo door and improved actuating mechanisms for: (i) permitting manually operable mechanical locking/unlocking of a fully closed and latched cargo door by ground personnel from the exterior of the aircraft without the need to employ ladders, ramps or similar ground equipment--i.e., the exterior locking/unlocking mechanism is readily accessible to personnel standing on the ground at a terminal gate or the like; (ii) permitting electrically operated latching/unlatching of a fully closed cargo door from the exterior of the aircraft by ground personnel only when the door locking mechanism is unlocked; and (iii), permitting electrically powered opening/closing of the aircraft cargo door only when the door is fully unlocked and unlatched. While the latch/unlatch and door open/close actuating mechanisms are preferably electrically operated as contrasted with the manually operated mechanical locking/unlocking mechanism, provision may be made for permitting manual operation thereof. Moreover, provision may also be made for permitting actuation of all of the actuating mechanisms from the interior of the cargo hold.
In accordance with the invention, the various actuating mechanism are designed and interrelated such that the cargo door is essentially fail-safe--that is, the unlatching and hinge actuating mechanisms can be actuated to open the cargo door only when the door is unlocked and the vent doors are opened to equalize exterior and interior cabin pressure, while the vent doors can be closed and the latch mechanisms locked only when the cargo door is fully closed and the latch mechanisms properly positioned in the fully latched condition.
2. Background Art
Conventional commercial aircraft are commonly provided with a multiplicity of ingress and egress openings in the lower lobe of the aircraft fuselage for permitting on-loading and off-loading of baggage, cargo and the like into and from the cargo hold, and with suitable doors being provided for closure of such openings. The doors vary widely in terms of their construction and operation. However, such cargo doors are commonly electrically powered, outwardly opening, canopy-type doors as contrasted with inwardly opening plug-type doors of the type often used to permit passenger ingress and egress. Such canopy-type cargo doors must be designed such that the interior aircraft cabin can be pressurized only when the doors are fully and properly closed and latched; and, to this end, it has been a common practice to provide relatively small vent doors in the cargo door with the cargo door and vent door actuating mechanisms being so designed and interrelated that closure of the vent doors is precluded in the event that the cargo door is not fully and properly closed and latched, thereby preventing pressurization of the interior compartments of the aircraft. A typical disclosure of such a known approach can be found in U.S. Pat. No. 2,748,855--Siems et al assigned to the assignee of the present invention.
As the aircraft industry has become more highly mechanized and the cargo capacity of relatively large aircraft has increased, it has become commonplace to employ relatively sophisticated cargo/baggage handling systems which enable the on-loading and off-loading of containerized and/or palletized cargo occupying relatively large volumes of space; and, as such cargo handling systems, cargo containers and cargo pallets have increased in size, it has been necessary to increase the size of the cargo ingress/egress openings in the aircraft fuselage and, therefore, to employ relatively large cargo doors to close such openings. And, of course, as the cargo doors have increased in size and weight, the actuating mechanisms for opening/closing, latching/unlatching, and locking/unlocking the doors have become more complex and bulky. In many instances, a significant proportion of such actuating mechanisms are mounted on the fuselage body structure and/or interconnected to the cargo door in such a manner that the actuating mechanisms project through the fuselage ingress/egress opening when the cargo door is opened, thereby significantly decreasing the effective area of the opening and limiting the size of the cargo containers and/or pallets that can be freely passed through such opening. Moreover, as the cargo storage capacity of such aircraft has increased, so too has the size of the ingress/egress openings in the fuselage body structure; and, as a consequence, when the aircraft is fully loaded, resulting distortions in the fuselege body structure tend to produce severe alignment problems when attempting to close the cargo door. Such misalignment often results in jamming of the door latching and/or locking mechanisms.